Domain-specific perceptual grouping of human dyads: evidence from autistic trait profiles.

A longstanding debate in social cognition centres on distinguishing between cognitive processes that are specialised for social content and those that function across multiple domains. Recent research shows that the visual processing of human figures in apparent social interactions is marked by early perceptual grouping. However, whether perceptual grouping of social scenes occurs through a social-specific or domain-general mechanism remains unclear. We examined this question by investigating the relationship between individual differences in social aptitude and perceptual grouping in geometric and social domains. Participants (n = 172) completed selective and integrative attention tasks featuring visual displays of geometric and human dyads. Their accuracy and reaction times were measured, and individual social traits were assessed using Autism Quotient Questionnaire subscales. Both geometric and social stimuli showed significant perceptual grouping effects, characterised by faster processing under integrative attention and slower processing under selective attention. Notably, individuals with higher social autistic traits tended to show selective difficulties in social perceptual grouping while maintaining intact geometric grouping, a pattern consistent with domain-specific processes in social scene processing. These findings suggest that even fundamental visual processes may be specifically tuned for social perception, with potential implications for understanding individual differences in social cognition.